No, seriously, if you want to find out the sad sad (but HILARIOUS) truth about Spock's childhood on Vulcan and his pet sehlat, you have to watch the animated series--it's the second episode. It's awesome.

The thing about Vulcan logic is that makes it them do illogical things. Like Sarek being near death but a) not telling anyone and b) going on the mission to Babel (OH CLEVER SHOW CLEVER) anyway.